The first episode was broadcast by the BBC on November 16, 1969 and a further twenty-five episodes were made. The twenty sixth episode was broadcast on November 10, 1972 and the final Clangers programme was a four minute election special on October 10, 1974. (This last episode has not been seen since its original broadcast, although it still exists in the BBC archive. A short clip is available at the BBC's website )
The programme featured a number of small creatures living in peace and harmony on - and in - a small, hollow planet far far away, nourished by Blue String Pudding, and Green Soup harvested from the planet's volcanic soup wells by the Soup Dragon. The Clangers looked similar to mice, anteaters and, from their pink colour, pigs. They wore clothes reminiscent of Roman armour and spoke in whistles.
The word "Clanger" is said to derive from the sound made by opening the metal cover of one of the creatures' crater-like burrows. Each of these is covered with a door made from an old metal dustbin lid, which is there to protect against meteorite impacts.
The first recorded sighting of a Clanger was in the 1967 Noggin the Nog book The Moon Mouse.
One of the most noted aspects of the programme was its use of sound effects, as this was the Clangers' sole form of communication, and score composed by Vernon Elliot under instructions from Oliver Postgate. Most of the music used over the two series was written by Postgate in the form of "musical sketches" or graphs which he drew for Elliot who would then convert the drawings into musical score. The music would then be recorded by the two along with other musicians, dubbed the Clangers ensemble, in a village hall where they would often leave the windows open leading to the sounds of birds outside being heard on some recordings. Much of the score was performed on Elliot's bassoon and also included the sounds of harps, clarinet, glockenspiel and bells.
The distinctive whistles made by the Clangers, performed on swanee whistles, have become as identifiable as the characters themselves and are much imitated amongst viewers of the programme. The series creators have said that the Clangers, living in vacuum, did not actually communicate by sound, but rather by a type of nuclear magnetic resonance, which was translated to audible whistles for the human audience. These whistles followed the rhythm and intonation of a script in the English language, including swear-words. The action was also narrated by a separate voice-over from Postgate, however the series was shown without narration to a group of overseas students, who each felt that the Clangers were speaking their own language.
In 2001, a selection of the series' music and sound effects was compiled by Jonny Trunk from 128 musical cues held by Oliver Postgate who contributed act one, "The Iron Chicken and the Music Trees", of A Clangers Opera, with libretto, which he had personally compiled.
There was also an election special produced in 1974 entitled "Vote for Froglet".